Difference in action between oral triazolam and zopiclone.

The effects of oral triazolam 0.25 mg and zopiclone 7.5 mg in 7 supine volunteers were compared by means of quantitative measurements of the EEG, saccadic eye movements, visual analogue scale (VAS) for alertness, critical flicker fusion frequency (CFF) and the Maddox wing. Zopiclone reached its maximum effect earlier (62 min) than triazolam (91 min; CFF). On linear regression analysis the average rate constant (regression coefficient) of onset of action of zopiclone was significantly greater than that of triazolam (0.29 vs. 0.17). Triazolam and zopiclone had similar effects, but zopiclone seemed to have a faster onset of action, probably indicating swifter absorption in supine subjects. Quantitative EEG evaluation gave parallel results to the other parameters used, but triazolam and zopiclone showed a dissimilar mechanism of action, as characterized by changes in the alpha frequency.